diff --git a/SConstruct b/SConstruct
index 7dadd94fd..f6d826edf 100644
--- a/SConstruct
+++ b/SConstruct
@@ -732,7 +732,7 @@ class DXXProgram(DXXCommon):
 	}])
 	objects_similar_arch_sdlmixer = DXXCommon.create_lazy_object_property([{
 		'source':[os.path.join('similar', f) for f in [
-'arch/sdl/digi_mixer.c',
+'arch/sdl/digi_mixer.cpp',
 'arch/sdl/jukebox.c'
 ]
 ],
diff --git a/common/include/digi_mixer.h b/common/include/digi_mixer.h
index a9d14cbd6..694913d79 100644
--- a/common/include/digi_mixer.h
+++ b/common/include/digi_mixer.h
@@ -3,6 +3,10 @@
 
 #include "maths.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 int digi_mixer_init();
 void digi_mixer_close();
 int digi_mixer_start_sound(short, fix, int, int, int, int, int);
@@ -19,4 +23,8 @@ void digi_mixer_stop_all_channels();
 void digi_mixer_set_digi_volume(int);
 void digi_mixer_debug();
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif
diff --git a/similar/arch/sdl/digi_mixer.c b/similar/arch/sdl/digi_mixer.cpp
similarity index 100%
rename from similar/arch/sdl/digi_mixer.c
rename to similar/arch/sdl/digi_mixer.cpp